Progress and challenges of contaminate removal from wastewater using microalgae biomass.

Progress and challenges of contaminate removal from wastewater using microalgae biomass

Environment-enhancing process for algal wastewater treatment, heavy metal control and hydrothermal biofuel production: A critical review.

Water pollution has grown to be a grave concern in the world. Direct discharge of wastewater poses risks to the aquatic ecosystems by causing eutrophication and degrades their physico-chemical characteristics. Moreover, wastewater is mainly enriched with recalcitrant toxic substances that pose detrimental impacts on the receiving environments. Conventional treatment approaches are mostly applied to remove nuisance pollutants from aquatic systems but are expensive and inefficient. Exploring microalgae has been found to be an efficient and ecofriendly technique for purification of aquatic environs. Furthermore, microalgae can effectively remove N (90–98.4%), P (66%–98%), Pb (75%–100%), Zn (15.6–99.7%), Cr (52.54%–96%), Hg (77%–97%), Cu (45%–98%) and Cd (2–93.06%)from contaminated aquatic systems. Microalgae play a pivotal role in degrading the complex pesticides ( α -endosulfan, lindane, isoproturon and glyphosate) and emerging concerned contaminants (triclosan, bisphenol A, 17 α -ethinylestradiol, tramadol and diclofenac) in elegant manner from disturbed environs. Apart from toxic pollutant removal, microalgae produce biomass, thereby acts as the efficient source of additional products like biofuel, carbohydrates, lipids and proteins which can make phycoremediation more frugal and sustainable.

Microalgae in aquatic environs: A sustainable approach for remediation of heavy metals and emerging contaminants

Sulfate can be presented as a chemical pollutant in some industrial wastewaters such as wastewater from power plants. Sulfate causes several problems in water and wastewater treatment including the corrosion of pipes and disruption of anaerobic processes. There are chemical, membrane, and biological methods to omit sulfate pollutant from wastewater. Microalgae have the dual role in wastewater treatment and biodiesel production. In this study, microalgae were used to reduce sulfate pollutant and to produce biomass from the combined-cycle power plant wastewater (5200 mg/L sulfate concentration). To do so, the growth of five microalgae (Chlorella sp., Chlamydomonas sp., Oocystis sp., Scenedesmus sp., and Fischerella sp.), production of biomass, and elimination of sulfate were evaluated in a batch culture system. Results indicated that microalgae can reduce the amount of sulfate pollutant and produce biomass. In addition, it was found that Oocystis sp. had a higher sulfate uptake rate (32%) than other microalgae. However, maximum biomass productivity was found to be 50 mg/L.d for Chlorella sp. Finally, the results showed that microalgae can be used to treat wastewater for sulfate reduction and production of microalgae biodiesel.

Cultivation of microalgae in a power plant wastewater for sulfate removal and biomass production: A batch study

The present investigation was attempted to reduce the toxic pollutants from the different mixtures of water samples (sewage, sea and well) using the freshwater alga, Chlorella vulgaris and the marine alga Chlorella salina. The results revealed that both algae species were highly efficient and having a potential to reduce pH, total dissolved solids (TDS), biological oxygen demand (BOD), chemical oxygen demand (COD), nitrate, ammonia, phosphate, sulphate, calcium, magnesium, sodium, potassium, heavy metals (Zn, Cu, Mn, Ni, Co, Fe and Cr) and the number of total Coli-form bacteria after 10 days of treatment compared to the untreated water samples. The removal efficiency of heavy metals was 13.61–100 %. In general, C. vulgaris shows higher removal efficiency in most of parameters than C. salina.

Bioremediation of different types of polluted water using microalgae

The present research was conducted to evaluate the marine algal extracts effectiveness on tomato Fusarium wilt disease. The organic extracts of macroalgae exhibited antagonistic activity against Fusarium oxysporum. The highest antifungal activity obtained from the methanolic extract of Cystoseira myrica followed by methanol extract of Sargassum cinereum. GC–mass analysis of some seaweed extracts was used to identify the presence of main compounds as dimethylocta-1,6-dien-3-ol,1-methoxy-4-(2-propenyl), hexadecanoic acid, methyl ester, and octadecanoic acid, and methyl ester. The infection of tomato plants with F. oxysporum induced a significant decrease in shoot and root dry weights as well as the photosynthetic pigments. There was a marked increase in soluble contents of saccharides and protein for infected tomato plant shoots and roots. On the other hand, pathogenicity stress induced a significant decrease in total contents of saccharides and protein of tomato shoots and roots. The results indicated a significant increase in total free amino acid content and antioxidant enzymes (CAT, POD, and APX) activities of inoculated tomato shoots and roots. The plant fresh and dry weights increased significantly by increasing its pigments content as a result of marine algal extracts application. On the other hand, algal extracts pretreatment decreased soluble saccharides and protein contents of plants, whereas increased significantly amino acid content in shoots of the inoculated plants. The increase in the activity of antioxidant enzymes played an essential role in increasing plant resistance against F. oxysporum. Finally, the marine macroalgae could serve as a new bioagent source for biological control of soil fungi.

Biological Control of Fusarium Wilt Disease of Tomato Plants Using Seaweed Extracts

This study was carried out to evaluate the antibacterial activity of ethanol, methanol, acetone, and ethyl acetate extracts of the brown seaweeds, Cystoseira myrica, Padina boergesenii and Sargassum cinereum (Phaeophyta), as well as to identify the phytochemical constituents of the most effective algal extracts. Antibacterial activities were expressed as inhibition zones and minimum inhibitory concentrations (MICs) of the algal extracts. All seaweed extracts tested exhibited a broad spectrum of antibacterial activity. The maximum inhibition activities were recorded for methanolic extracts of P. boergesenii and ethyl acetate extracts of C. myrica and S. cinereum against Shigella flexneri, Staphylococcus aureus (MRSA) and Staphylococcus aureus, respectively. The MIC values of the marine algal extracts tested for inhibiting pathogenic bacteria ranged from 3.13 to 300 mg/ml. GC-MS and FTIR analyses of algal extracts revealed the chemical components and their functional constituents in the brown seaweeds that might have potent antimicrobial activities. These components include fatty acids esters, alcohols, phenols, amines-containing compounds and others. The results indicated that brown seaweeds may be main sources of phytoconstituents which exhibited antibacterial properties and will be helpful in diminishing the adverse effects of synthetic drugs.

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Antibacterial efficacy and phytochemical characterization of some marine brown algal extracts from the red sea, Egypt

Seaweeds are becoming a viable source of biologically active composites with a hopeful application as nutraceuticals, functional food components, and medicinal agents. In the present study, the antioxidant capacity and biochemical compositions of four seaweeds; Polycladia indica and Turbinaria ornata (Phaeophyceae) and Laurencia obtusa and Sarconema scinaioides (Rhodophyceae), were estimated. The results indicated that T. ornata showed the maximum value of total phenolic compound (TPC), flavonoid content, β-carotene, carbohydrate and has maximum percentage of DPPH radical scavenging capacity, total antioxidant capacity (TAC), and total reducing capacity (TRC) (72.48%, 15.02%, and 53.24% inhibition, respectively), while the highest contents of ascorbic acid, lipid, calcium, and zinc were observed in L. obtusa. P. indica showed the highest protein contents, dietary fibers, sodium, potassium, magnesium, and total amino acids. Glutamic, aspartic, proline, and methionine were the most frequent amino acids in the four selected seaweeds. Brown seaweeds (T. ornata and P. indica) attained the highest percent of the total polyunsaturated (ω6 and ω3) essential fatty acids. The biochemical content of these seaweed species, as well as their antioxidant properties, make them interesting candidates for nutritional, pharmacological, and therapeutic applications.

Assessment of Antioxidant Capacity and Phytochemical Composition of Brown and Red Seaweeds Sampled off Red Sea Coast

This study demonstrates the combination of wastewater treatment and green microalgae cultivation for the low-cost production of lipids as a feedstock for biodiesel production. Three green microalgal species were used: Chlamydomonas reinhardtii, Monoraphidium braunii, and Scenedesmus obliquus. Nutrient, heavy metals and minerals removal, biomass productivity, carbohydrate, protein, proline, lipid, and fatty acids methyl ester (FAMEs) contents besides biodiesel properties were evaluated. The results showed that all algal species were highly efficient and had the potential to reduce nitrate, ammonia, phosphate, sulfate, heavy metals (Zn2+, Cu2+, Mn2+, and Fe2+), calcium, magnesium, sodium, and potassium after 10 days of algal treatment compared to initial concentrations. The removal efficiency of these parameters ranged from 12 to 100%. The growth rates of M. braunii and S. obliquus cultivated in wastewater were significantly decreased compared to the control (synthetic medium). In contrast, C. reinhardtii showed the highest growth rate when cultivated in sewage water. Wastewater could decrease the soluble carbohydrates and protein content in all tested algae and increase the proline content in M. braunii and S. obliquus. In wastewater culture, M. braunii had the highest lipid productivity of 5.26 mg L-1 day-1. The fatty acid profiles of two studied species (C. reinhardtii and M. braunii) revealed their suitability as a feedstock for biodiesel production due to their high content of saturated fatty acids, representing 80.91% and 68.62% of the total fatty acid content, respectively, when cultivated in wastewater. This study indicated that wastewater could be used to modify biomass productivity, lipid productivity, and the quantity of individual fatty acids in some algae that affect biodiesel quality to achieve international biodiesel standards. 

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Abla A. M. Farghl

Papers

Bioremediation of different types of polluted water using microalgae

Biological Control of Fusarium Wilt Disease of Tomato Plants Using Seaweed Extracts

Antibacterial efficacy and phytochemical characterization of some marine brown algal extracts from the red sea, Egypt

Assessment of Antioxidant Capacity and Phytochemical Composition of Brown and Red Seaweeds Sampled off Red Sea Coast

Coupling wastewater treatment, biomass, lipids, and biodiesel production of some green microalgae